I had to completely uninstall RF2 and my DLC, which is GTE, GT3 Challenger, GT3 and Sebring. RF2 installed correctly, but Steam is saying I have no additional DLC at all even though in my purchase history on Steam it shows all my purchases for all the DLC. So why is Steam saying I have no DLC for RF2 when they are showing my purchase history having the aforementioned DLC? So the problem is that I cannot get all my purchased content beyond RF2 itself.
RF2 cars and tracks aren't listed as DLC on Steam but as inventory items, check there and subscribe to each one again if needed.
I did want to mention that all the content in my inventory was already subscribed. So I had to unsubscribe and resubscribe to all of them to get it to work.